In order to test whether gene-engineered endothelial cells would adhere and thrive and express a recombinant marker when introduced into a segment of arterial graft, it is necessary to provide a mock circulatory system or surgically implant the graft into a living host animal. The present work provides a system whereby tissue culture fluid is presented to the graft segment containing the altered cells at pulse pressures and flow values mimicking host that would be encounted by a graft implanted in a living animal. The mock circulation is designed to maintain a biochemical milieu consistent with optimal tissue growth and survival while challenging the adhesive and secretory activity through the mechanical forces tending to dislodge the grafted cells. Changes in the procedure such as the material of the graft and the provision of ports for insertion of a balloon catheter to insert a stent previously seeded with cells genetically modified to elaborate tissue plasminogen activator have been accomplished. Preliminary results demonstrated satisfactory survival and function of cells on the stents.